For the dielectrics used in electronic circuit elements, ceramics have conventionally been used as materials with a dielectric constant of about 10 or more. Using a material with a high dielectric constant allows the electronic circuit element to be miniaturized. It also has the advantage of reducing radiation loss because in the microwave, millimeter wave and other high frequency bands electromagnetic energy becomes concentrated in the dielectric. Application of ceramics to microwave communications devices has expanded in recent years, and materials with high dielectric constants and low dielectric loss are being developed.
A composite dielectric of conductive powder mixed with resin has been presented as a non-ceramic material having a dielectric constant of about 10 or more (Japanese Patent Publication No. S55(1980)-2044). A composite dielectric of dielectric powder mixed with resin has also been presented (Japanese Unexamined Patent Publication No. S58(1983)-166609). These composite dielectrics offer the feature of allowing the dielectric constant to be altered by changing the compounding ratio of powder in the matrix material, and have good cutting and other working properties.